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Journal of Zhejiang University SCIENCE B

ISSN 1673-1581(Print), 1862-1783(Online), Monthly

Rice bran oil supplementation protects swine weanlings against diarrhea and lipopolysaccharide challenge

Abstract: Early weaned piglets suffer from oxidative stress and enteral infection, which usually results in gut microbial dysbiosis, serve diarrhea, and even death. Rice bran oil (RBO), a polyphenol-enriched by-product of rice processing, has been shown to have antioxidant and anti-inflammatory properties both in vivo and in vitro. Here, we ascertained the proper RBO supplementation level, and subsequently determined its effects on lipopolysaccharide (LPS)-induced intestinal dysfunction in weaned piglets. A total of 168 piglets were randomly allocated into four groups of seven replicates (42 piglets each group, (21±1) d of age, body weight (7.60±0.04) kg, and half males and half females) and were given basal diet (Ctrl) or basal diet supplemented with 0.01% (mass fraction) RBO (RBO1), 0.02% RBO (RBO2), or 0.03% RBO (RBO3) for 21 d. Then, seven piglets from the Ctrl and the RBO were treated with LPS (100 μg/kg body weight (BW)) as LPS group and RBO+LPS group, respectively. Meanwhile, seven piglets from the Ctrl were treated with the saline vehicle (Ctrl group). Four hours later, all treated piglets were sacrificed for taking samples of plasma, jejunum tissues, and feces. The results showed that 0.02% was the optimal dose of dietary RBO supplementation based on diarrhea, average daily gain, and average daily feed intake indices in early weaning piglets. Furthermore, RBO protected piglets against LPS-induced jejunal epithelium damage, which was indicated by the increases in villus height, villus height/crypt depth ratio, and Claudin-1 levels, as well as a decreased level of jejunal epithelium apoptosis. RBO also improved the antioxidant ability of LPS-challenged piglets, which was indicated by the elevated concentrations of catalase and superoxide dismutase, and increased total antioxidant capacity, as well as the decreased concentrations of diamine oxidase and malondialdehyde in plasma. Meanwhile, RBO improved the immune function of LPS-challenged weaned piglets, which was indicated by elevated immunoglobulin A (IgA), IgM, β‍‍-defensin-1, and lysozyme levels in the plasma. In addition, RBO supplementation improved the LPS challenge-induced dysbiosis of gut microbiota. Particularly, the indices of antioxidant capacity, intestinal damage, and immunity were significantly associated with the RBO-regulated gut microbiota. These findings suggested that 0.02% RBO is a suitable dose to protect against LPS-induced intestinal damage, oxidative stress, and jejunal microbiota dysbiosis in early weaned piglets.

Key words: Rice bran oil; Gut microbiota; Weaned piglets; Oxidative stress; Lipopolysaccharide

Chinese Summary  <35> 基于壁面函数大涡模拟研究横流通道对转静系盘腔流动特性的影响

作者:谢垒1,2,3,杜强1,2,3,柳光1,2,3,廉曾妍1,2,3,谢亚广1,2,3,罗一夫1,2,3
机构:1中国科学院工程热物理研究所,轻型动力实验室,中国北京,100190;2中国科学院大学,工程科学学院,中国北京,100049;3中国科学院轻型动力创新研究院,中国北京,100190
目的:本文旨在探究带有均匀预旋速度的外部横流对转静系盘腔流动特性的影响,从而指导对真实发动机条件下涡轮盘腔流动特性的研究。
创新点:1.采用壁面函数大涡模拟(WMLES)方法,获得了带有横流通道的转静系盘腔更为精细的流场结构;2.识别了盘腔轮缘处的开尔文-赫姆霍茨(K-H)不稳定性,并探究了K-H剪切涡结构对轮缘处流动特性的影响。
方法:1.通过高精度大涡模拟方法,捕捉流场中的精细化流场结构。2.结合理论推导,通过对于流动结构的机理和动力学分析,探究外部横流和盘腔耦合流动特性。
结论:1.由于雷诺平均(RANS)模拟对壁面小尺度涡结构和输运方程的解析能力不足,所以RANS模拟流场与WMLES模拟流场出现了明显偏差。2.在横流和盘腔流动的耦合作用下,由于轮缘处的速度剪切诱导产生K-H涡结构,所以这些涡结构将会加强轮缘处的外部入侵和盘腔出流流动。3.在外部入侵和盘腔出流的影响下,盘腔端区发现了大尺度流动结构;这些大尺度流动结构以一定的转速旋转,且其转速和数量可以通过快速傅里叶变换以及相关性分析确定。

关键词组:壁面函数大涡模拟;转-静系盘腔;流动不稳定性;RANS


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DOI:

10.1631/jzus.B2200565

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On-line Access:

2023-05-15

Received:

2022-11-07

Revision Accepted:

2023-01-27

Crosschecked:

2023-05-16

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